2500-Channel single-shot areal profilometer using hyperspectral interferometry with a pinhole array. (November 2019)

• Record Type: Journal Article
• Authors: Reichold, Tobias V.; Ruiz, Pablo D.; Huntley, Jonathan M.
• Is Part Of: Optics and lasers in engineering. Volume 122(2019)
• Page Start: 37
• Page End: 48
• Publication Date: 2019-11
• Subjects: 120.3930 -- 100.3175 -- 120.6650 -- 110.5086; Metrological instrumentation -- Interferometric imaging -- Surface measurements -- Phase unwrapping -- Pinhole array -- Hyperspectral; Lasers in engineering -- Periodicals; Optical measurements -- Periodicals; Optics -- Periodicals; Lasers en ingénierie -- Périodiques; Mesures optiques -- Périodiques; Optique -- Périodiques; 621.36605
• DOI: 10.1016/j.optlaseng.2019.05.015
• Languages: English
• ISSNs: 0143-8166

Abstract

Highlights: Single-shot hyperspectral areal profilometer without requiring mechanical scanning. 2500 independent measurement channels with 0.825 mm depth range. Improved object tilt angle acceptance up to 33.3 mrad. Phase unwrapping allows height measurements to a precision of ∼6 nm. Abstract: Surface profilometry techniques such as coherent scanning interferometry or focus variation require long scan times and are thus vulnerable to environmental disturbance. Hyperspectral interferometry (HSI) overcomes the problem by recording all the spatial and spectral information necessary to reconstruct a 2D surface height map in a single shot. In this paper, we present a new HSI system that uses a pinhole array to provide the necessary gaps for the spectral information. It is capable of measuring 2500 independent points, twice the previous maximum number, with a maximum unambiguous depth range of ∼825 µm and a larger maximum surface tilt angle of 33.3 mrad. The use of phase information allows height to be measured to a precision of ∼6 nm, an order of magnitude improvement on previous HSI systems.